This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-124104, filed Apr. 30, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an apparatus for processing a substrate characterized by supplying a process liquid such as a resist solution or a solvent onto a substrate such as a semiconductor wafer and a substrate for a liquid crystal display, and spreading the supplied process liquid by rotating the substrate in a cup. More specifically, the present invention relates to a method for washing the cup having the scattered process liquid attached thereon.
In manufacturing processes for a semiconductor device and liquid crystal display (LCD), etc., a photolithographic technique is used to form a desired circuit. In the photolithography technique, a resist solution is applied to a surface of the substrate such as a wafer, exposed to light together with a predetermined pattern, and subjected to a developing process. In this manner, a resist film having the predetermined pattern is formed on the substrate. Subsequently, the obtained resist film is subjected to etching, with the result that a circuit of the predetermined pattern is formed.
Today, a spin coating method is dominantly employed as a method of coating a resist solution onto a wafer. In the spin coating method, after a resist solution is supplied dropwise to a center of the wafer, the wafer is rotated at a high speed to apply centrifugal force to the resist solution. As a result, the resist solution is spread and coated over the entire surface of the wafer. At this time, excessively provided resist solution is removed by scattering it from the edge of the wafer by the centrifugal force. In the spin coating method, to receive the resist solution scattered from the wafer, the wafer is rotated within the cup. However, in this method, the resist solution scattered from the wafer is attached to an inner wall of the cup. Therefore, the cup must be washed occasionally as needed.
A technique for washing the process liquid attached to the inner wall of the cup is disclosed in U.S. Pat. No. 5,312,487. In the technique disclosed in the publication, a plate for distributing washing liquid exclusively used in washing process is employed. The plate is first loaded into a cup to be washed and held on the spin chuck. Then, the plate is rotated at a high speed. Subsequently, a washing liquid is supplied from the washing liquid supply nozzle which is placed right above the plate rotated at a high speed so as to face the plate. The supplied washing liquid is distributed and scattered from the edge portion of the plate by the centrifugal force produced by the rotation of the plate and blown onto the inner portion of the cup.
However, the aforementioned conventional technique has the following problems.
First, the conventional apparatus has a discrete solvent supply mechanism for supplying the washing liquid to the cup. Therefore, an entire structure of the apparatus is inevitably complicated and enlarged.
In addition, various types of the process liquids (for example, resist solution) have been increasingly used in recent years. With this tendency, stains formed on the cup are diversified in pattern. Never-theless, stains of various types of process liquids cannot be cleaned by the technique disclosed in the publication. To describe more specifically, the cup cannot be sufficiently cleaned in the cases where a hard-to-remove process liquid is used and where a low-viscosity process liquid is scattered over a broad range. To deal with this problem, the amount of washing liquid and the number of washing process must be increased. As a result, throughput is inevitably reduced.
In these circumstance, it is an object of the present invention to provide a substrate processing apparatus for washing out an attached material from the cup without making the apparatus complicated and enlarged.
Furthermore, the present invention is directed to a substrate processing method for efficiently washing an inner surface of the cup in the photolithography.
According to the present invention, there is provided an apparatus for processing a substrate by supplying a process liquid to a substrate to be processed in a photolithography, comprising a cup; a washing control plate for washing an inner surface of the cup; a spin chuck for rotating the washing control plate or the substrate while holding the washing control plate or the substrate substantially horizontally in the cup; a solvent supply mechanism for supplying a solvent capable of dissolving the process liquid, onto the washing control plate or the substrate held by the spin chuck; a process liquid supply mechanism for supplying the process liquid onto the substrate held by the spin chuck; and a control section for selecting either a solvent to be supplied to the substrate or a solvent to be supplied to the washing control plate and controlling the solvent supply mechanism in accordance with the solvent selected.
In this case, the control section has a supply-condition data storing portion for storing data of supply conditions of the solvents to the substrate and the washing control plate; and the control section controls the solvent supply mechanism on the bases of each of the supply condition data stored in the supply-condition data storing portion. Furthermore, it is desirable that the supply conditions for the solvent to be supplied to the washing control plate be determined in consideration of the process liquid.
The solvent supply mechanism has a solvent supply source, and a solvent feeding mechanism connected to the control section which controls a supply amount and/or supply time of the solvent from the supply source.
The solvent supply mechanism has an upper surface side supply system for supplying the solvent toward an upper surface of the washing control plate and a lower surface side supply system for supplying the solvent toward the lower surface of the washing control plate; and the control section controls so as to supply the solvent to the washing control plate by at least one of the upper surface side supply system and the lower surface side supply system.
The solvent supply mechanism has a solvent supply system for supplying the solvent to at least one of the upper and lower surfaces of the washing control plate, and a solvent spray system for supplying a misty solvent toward an inner surface of the cup; and
the control section supplies the misty solvent to an inner surface of the cup from the solvent spray system and thereafter supplies the solvent from the solvent supply system while the washing control plate is rotated.
The apparatus further comprises an atmosphere control mechanism for controlling an atmosphere of the cup, the atmosphere control mechanism being selectively controlled by the control section during a pre-processing time, processing time and a cup washing time.
The control section changes a rotation speed of the spin chuck to change a solvent supply position to the cup from the washing control plate.
The apparatus of the present invention further comprises a transfer mechanism for transferring the washing control plate onto the spin chuck.
The washing control plate further comprises a solvent guiding portion for scattering the solvent.
The solvent guiding portion has a guiding piece which is formed by partly cutting a peripheral portion of the washing control plate to make an incision and raising up the incision.
The solvent guiding portion has a guiding passage for guiding the solvent from a surface to which the solvent is supplied to an opposite surface thereof.
The apparatus of the present invention further comprises a substrate temperature control mechanism for setting temperatures of the washing control plate and the substrate substantially the same.
The spin chuck adsorbs and holds the washing control plate or the substrate at a predetermined distance therebetween.
According to the present invention, a method of processing a substrate by supplying a process liquid to the substrate in a cup in a photolithography, comprising the steps of:
(a) permitting the substrate to be held on a spin chuck arranged in the cup;
(b) moistening the substrate with the solvent by supplying a solvent onto the substrate by a solvent supply system while the substrate is rotated by the spin chuck;
(c) forming a film of a process liquid on the substrate by supplying a process liquid onto the substrate while rotating the substrate by the spin chuck;
(d) removing the substrate from the spin chuck and mounting a washing control plate onto the spin chuck; and
(e) supplying the solvent onto the washing control plate by using the same solvent supply system as in the step (b) while the washing control plate is rotated by the spin chick to scatter the solvent from the washing control plate toward an inner surface of the cup, thereby removing an attached material from the inner surface of the cup.
In the step (e), another solvent supply system is desirably used which differs from the solvent supply system used in the step (b).
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.